1. Field of the Invention
The present invention relates generally to energy storage and conversion systems, and more particularly to a system for storing electrical energy in the form of rotational momentum and for converting direct current power into alternating current power using a rotating mass as a buffer.
2. Description of the Prior Art
A need exists for inexpensive and reliable techniques for storing large amounts of electrical energy. Several techniques have been developed in the past, but many of these solutions are not practical in many environments. For example, systems have been developed in which excess electrical power is used to drive pumps which pump water into large storage facilities. When additional power is needed, the water from the storage facilities is drawn out through turbine wheels which convert the potential energy of the stored water into electrical energy. Although such systems work well in environments where large quantities of water are readily available, they are not practical in many parts of the country where water is not readily available and where the land is often flat, making the construction of elevated reservoirs extremely difficult and complex. Furthermore, water storage systems of the type described are generally feasible only for very large power stations since they are very expensive and complex to construct.
Energy storage devices are needed throughout the world for use in conjunction with many of the energy generating techniques which have been popularized by the recent shortage of fossil fuels. For example, there is now considerable interest in generating electrical power using naturally available sources of energy such as wind energy, solar energy, geothermal energy and others. Many of these sources such as wind energy and solar energy are discontinuous in a time frame which is often not compatable with output power requirements. For example, no solar energy is available at night when there is a need for output power to drive lighting fixtures.
Thus there is a need to accumulate the energy derived from discontinuous natural sources of this type until a need for the energy develops. Naturally, such systems which remove energy from nature at no cost and store it until a need for the energy arises can be of great economic and commercial importance as the cost of fossil fuels and other techniques of generating energy increase dramatically.
It is also desirable that an energy storage apparatus for use in conjunction with energy sources of the type described be capable of converting direct current power into alternating current power since it is often easiest to convert some forms of natural energy, such as solar energy, into direct current, while most commercial appliances require alternating current power. Thus it is highly desirable that the energy storage means, in addition to providing a temporary storage function, also provide the capability of converting from direct to alternating current power.